An organic light emission phenomenon is an example of the conversion of current into visible light by the internal process of a specific organic molecule. The principle of the organic light emission phenomenon is as follows. When an organic material layer is placed between an anode and a cathode, if voltage is applied to the specific organic molecule through two electrodes, electrons and holes from the cathode and the anode, respectively, flow into the organic material layer. The electrons and the holes injected into the organic material layer are recombined to form excitons, and these excitons fall back to the ground state and emit light. An organic light emitting device using this principle may include, generally, a cathode, an anode, and an organic material layer placed therebetween, for example, an organic material layer that includes a hole injection layer, a hole transfer layer, a light emitting layer and an electron transfer layer.